Abstract: Despite being the prototype of its class, T Pyx is arguably the most unusual
and poorly understood recurrent nova. Here, we use radio observations from the
Karl G. Jansky Very Large Array to trace the evolution of the ejecta over the
course of the 2011 outburst of T Pyx. The radio emission is broadly consistent
with thermal emission from the nova ejecta. However, the radio flux began
rising surprisingly late in the outburst, indicating that the bulk of the
radio-emitting material was either very cold, or expanding very slowly, for the
first ~50 days of the outburst. Considering a plausible range of volume filling
factors and geometries for the ejecta, we find that the high peak flux
densities of the radio emission require a massive ejection of 1-30 x 10^{-5}
solar masses. This ejecta mass is much higher than the values normally
associated with recurrent novae, and is more consistent with a nova on a white
dwarf well below the Chandrasekhar limit.